Rotary head cleaning device

ABSTRACT

A cleaning device capable of cleaning a rotary head without discharging static electricity to a magnetic head is provided. The cleaning device comprises a protruding shaft-like supporting member provided at a position in a housing facing a portion of the outer peripheral surface of a rotary drum and opposite a portion in contact with a magnetic tape, and a cylindrical cleaning member supported at the upper end of the supporting member. The supporting member is configured with a metal material, and is electrically connected with the housing. The cleaning member is made of an electrically conductive resin in which carbon particles are contained. When and while the outer peripheral surface of the cleaning member is in contact with the outer peripheral surface of the rotary drum, the cleaning member is electrically connected with the housing through the supporting member.

CROSS REFERENCE TO RELATED APPLICATIONS

The present document claims priority to Japanese Priority Document JP2001-248540, filed in the Japanese Patent Office on Aug. 20, 2001, theentire contents of which are incorporated herein by reference to theextent permitted by law.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a cleaning device for a rotary head.

2. Description of the Related Art

FIG. 6 is a schematic drawing showing an example of a conventionalcleaning device for a rotary head.

As shown in FIG. 6, a rotary head 10 of a magnetic tape recording andreproducing apparatus has a fixed drum 1002 installed in a housing 20, arotary drum 1004 installed above the fixed drum 1002, and a magnetichead 1006 attached to the rotary drum 1004.

Two fixed guides 1008, two first guide rollers 1010 and two second guiderollers 1012, which all guide a magnetic tape 1 in its running directionrelative to the rotary head 10, are each disposed upstream anddownstream with respect to the running direction of the magnetic tape 1with the rotary head 10 between each of the pairs.

A cleaning device 30 is disposed at a position of the housing 20 facinga portion of the outer peripheral surface of the rotary drum 1004opposite a portion in contact with the magnetic tape 1. The cleaningdevice 30 comprises a shaft-like supporting member 3002 provided in thehousing 20, and a cylindrical cleaning member 3004 attached to the upperend of the supporting member 3002.

The cleaning member 3004 is made of, for example, urethane or the like,and is installed such that its outer peripheral surface contacts theouter peripheral surface of the rotary drum 1004.

In this structure, the rotary drum 1004 rotates, and the cleaning member3004 contacts the outer peripheral surface of the rotary drum 1004 andthe magnetic head 1006 to clean residual dirt, such as abraded powderdebris from magnetic tapes, built-up thereon.

FIG. 7 is a schematic drawing showing another example of a conventionalcleaning device for a rotary head.

In the example, a cleaning device 40 comprises a tape-like cleaningmember 4002 made of urethane or the like, two rolls 4004 around whichboth ends of the cleaning member 4002 are wound, and two protrudingshaft-like guides 4006 provided in the housing 20.

The cleaning device 40 is structured such that one of the surfacesperpendicular to the thickness of the cleaning member 4002, guided bythe two guides 4006, contacts the rotary drum 1004 along the outerperipheral surface of the rotary drum 1004 with a predetermined tension.

In this structure, the rotary drum 1004 rotates, and the surface of thecleaning member 4002 mentioned above contacts the outer peripheralsurface of the rotary drum 1004 and the magnetic head 1006 to cleanresidual dirt, such as abraded powder debris from magnetic tapes,built-up thereon.

However, in the conventional cleaning devices for rotary heads describedabove, because the cleaning members 3004 and 4002 are made ofnonconductive material such as urethane or the like, there is apossibility that the magnetic head 1006 could suffer electrostaticdamage caused by static electricity generated through friction betweenthe cleaning members 3004, 4002 and the outer peripheral surface of therotary drum 1004. In particular, if the magnetic head 1006 comprises amagneto-resistive type head, due to its own properties, there is aproblem in that the magnetic head 1006 is prone to electrostatic damage.

SUMMARY OF THE INVENTION

The present invention is proposed in consideration of such problems. Itis an aspect of the present invention to provide a cleaning device for arotary head capable of performing cleaning of a rotary head drum withoutdischarging static electricity to a magnetic head provided with therotary head.

In order to achieve the aspect above, the present invention isstructured such that, in a cleaning device for a rotary head forcleaning the rotary head by bringing a cleaning member into contact withthe rotating head inside a housing, the cleaning member is formed of amaterial having electrical conductivity and the cleaning member isgrounded to the housing.

Consequently, according to an embodiment of the present invention,because static electricity generated through contact between thecleaning member and the rotary head flows from the cleaning member tothe housing, no static electricity is applied to the magnetic head.

As described above, according to the rotary head cleaning device of thepresent invention, the cleaning of the rotary head can be performedwithout having static electricity applied to a magnetic head providedwith the rotary head.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will become more apparent from the following description ofthe presently preferred exemplary embodiments of the invention taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a schematic drawing showing a rotary head cleaning device of afirst embodiment of the present invention;

FIG. 2 is a schematic drawing showing a variation of the rotary headcleaning device of the first embodiment of the present invention;

FIG. 3 is a schematic drawing showing a rotary head cleaning device of asecond embodiment of the present invention;

FIG. 4 is a schematic drawing showing a variation of the rotary headcleaning device of the second embodiment of the present invention;

FIG. 5A is an explanatory diagram showing measurement results of thepreventive effect against electrostatic damage to a magnetic head whencleaning operations are performed on a rotary head in a condition where,in the first embodiment, a cleaning member is grounded to a housing;

FIG. 5B is an explanatory diagram showing measurement results of thepreventive effect against electrostatic damage to the magnetic head whencleaning operations are performed on the rotary head in a conditionwhere, in the first embodiment, the cleaning member is not grounded tothe housing;

FIG. 6 is a schematic drawing showing an example of a conventionalrotary head cleaning device; and

FIG. 7 is a schematic drawing showing another example of a conventionalrotary head cleaning device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments for the cleaning device of the present inventionare described below with reference to the accompanying drawings.

FIG. 1 is a schematic drawing showing a cleaning device according to afirst embodiment. Like components found in FIGS. 6 and 7 showingconventional examples are designated by identical reference numerals inFIG. 1.

As shown in FIG. 1, a rotary head 10 of a magnetic tape recording andreproducing apparatus comprises a fixed drum 1002 provided in a housing20, a rotary drum 1004 provided above the fixed drum 1002, and amagnetic head 1006 attached to the rotary drum 1004. A guide, not shownin drawing, for guiding the running of a magnetic tape 1 is provided onthe outer peripheral surface of the fixed drum 1002. The housing 20 ismade from an electrically conductive material. A cleaning device 50,which will be described later, is disposed close to the rotary head 10.

In the present specification, the housing 20 includes a chassis, a frameand a cover.

Two fixed guides 1008, two first guide rollers 1010 and two second guiderollers 1012, which all guide the magnetic tape 1 in its runningdirection relative to the rotary head 10, are each disposed upstream anddownstream with respect to the running direction of the magnetic tape 1with the rotary drum 1004 between each of the pairs.

The first guide rollers 1010 are each structured to include a rollersection driven by the running of the magnetic tape 1 to rotate and anon-rotating flange provided on an upper portion of the roller sectionand which regulates the upper edge of the magnetic tape 1.

The second guide rollers 1012 are each structured to include a rollersection which rotates along with the running magnetic tape 1 and anon-rotating flange provided on a lower portion of the roller sectionfor regulating the lower edge of the magnetic tape 1.

By having the upper edge of the magnetic tape 1 regulated by the flangesof the first guide rollers 1010 and having the lower edge of themagnetic tape 1 regulated by the flanges of the second guide rollers1012, the lower edge of the magnetic tape 1 runs along the guide of thefixed drum 1002. Thus, the magnetic head 1006 traces the right tracks onthe magnetic tape 1.

The magnetic head 1006 comprises a magneto-resistive type head.

The magneto-resistive type head includes a magneto-resistive (MR) head,a giant magneto-resistive (GMR) head, a tunneling magneto-resistive(TMR) head, and the like.

The MR head utilizes the principle that, when an electric current flowsthrough an element made of a material, such as Permalloy, showing amagneto-resistive effect (MR effect), the electrical resistance of theelement changes according to the angle formed between the direction inwhich the electric current flows and the direction of an externalmagnetic field. That is, the MR head is structured to perceive changesin an external magnetic field by measuring changes in electricalresistance.

The GMR head, like the MR head, utilizes the magneto-resistive effect,but its element is configured in a film structure in which aferromagnetic layer, a non-magnetic layer and a ferromagnetic layer arelayered on one another and an anti-ferromagnetic layer is formedadjacent thereto.

The TMR head is a magneto-resistive type head which makes use of tunnelconduction.

The cleaning device 50 comprises a protruding shaft-like supportingmember 5002 provided at a position in the housing 20 facing a portion ofthe outer peripheral surface of the rotary drum 1004, and opposite aportion of the outer peripheral surface with which the magnetic tape 1is in contact, and a cylindrical cleaning member 5004 supported at theupper end of the supporting member 5002.

The supporting member 5002 is made of a metal material, and iselectrically connected with the housing 20. The cleaning member 5004 ismade of an electrically conductive resin containing carbon particlessuch that its electrical resistance is 10¹⁰ Ω or less.

The cleaning member 5004 is provided with a bearing (not shown) intowhich ball bearings are incorporated. The cleaning member 5004 issupported by the supporting member 5002 to be rotatable via the bearing.Both the ball bearing and the bearing are made of a conductive material,and there is conductive grease between the ball bearing and the bearing.

Thus, the cleaning member 5004 is structured to be driven to rotate bythe rotations of the rotary drum 1004 in a condition where the cleaningmember is located at a cleaning position at which the outer peripheralsurface thereof contacts the outer peripheral surface of the rotary drum1004. Further, the cleaning member 5004 is electrically connected withthe housing 20 via the bearing, the conductive grease, the ball bearingand the supporting member 5002.

According to the configuration described above, residual dirt, such asabraded powder debris from magnetic tapes, on the outer peripheralsurface of the rotary drum 1004 and on the magnetic head 1006 is cleanedas the cleaning member 5004 contacts the outer peripheral surface of therotary drum 1004 and the magnetic head 1006 while the rotary drum 1004rotates.

Static electricity generated due to contact between the cleaning member5004 and the outer peripheral surface of the rotary drum 1004 and themagnetic head 1006 flows to the housing 20 via the cleaning member 5004,the bearing, the conductive grease, the ball bearing and the supportingmember 5002.

Consequently, no static electricity is applied to the magnetic head1006, and electrostatic damage can thereby be prevented.

FIG. 2 is a schematic drawing showing a variation of the cleaning deviceof the first embodiment.

In a cleaning device 50A, the supporting member 5002 is supported at afulcrum 5006 so as to be swingable towards the housing 20, and theplunger 5010 of a solenoid 5008 is connected with the supporting member5002.

Further, the cleaning device 50A is configured such that the supportingmember 5002 is caused to swing by an on/off operation of the solenoid5008. Accordingly, the cleaning member 5004 is disposed so as to bemovable between a cleaning position where the cleaning member 5004contacts the rotary head 10 and a non-cleaning position away from therotary head 10.

In this variation too, as in the first embodiment above, staticelectricity generated due to contact between the cleaning member 5004and the outer peripheral surface of the rotary drum 1004 and themagnetic head 1006 flows to the housing 20 via the cleaning member 5004,the bearing, the nonconductive grease, the ball bearing and thesupporting member 5002. Consequently, static electricity is not appliedto the magnetic head 1006, and electrostatic damage can be prevented.

FIG. 3 is a schematic drawing showing a cleaning device according to asecond embodiment. Like components found in FIGS. 6 and 7 are designatedby the same reference numbers in FIG. 3.

A cleaning device 60 is made of a tape-like cleaning member 6002, tworolls 6004 to which both ends of the cleaning member 6002 are wound andwhich are provided so as to be rotatble relative to a housing 20, andtwo protruding shaft-like guides 6006 provided at a position in thehousing 20 close to a rotary head 10.

The cleaning member 6002 is made of a synthetic resin as its base, andpolishing surfaces are formed on both surfaces of the cleaning member6002 which are perpendicular to the thickness thereof. Carbon particlesare included in the material of the polishing surfaces, and consequentlythe polishing surfaces, that is, the cleaning member 6002, areconfigured to have an electrical resistance of 10¹⁰ Ω or less. In otherwords, the cleaning member 6002 is formed to have electricalconductivity.

Each of the rolls 6004 is made of a metal material, and is rotatablysupported by a bearing (not shown) provided in the housing 20 and intowhich a ball bearing is incorporated. Moreover, each of the rolls 6004is configured to wind the cleaning member 6002 from one roll 6004 to theother roll 6004 by being rotated by rotating and driving means (notshown). And the rolls 6004 are configured such that they provide tensionto the cleaning member 6002 between the rolls 6004 by way of the drivingforce of the rotating and driving means.

Both the ball bearing and the bearing are made of a material havingelectrical conductivity, and there is conductive grease between the ballbearing and the bearing.

The guides 6006 are made of a metal material, and are electricallyconnected with the housing 20.

The cleaning device 60 is structured such that the cleaning member 6002is guided by the two guides 6006 in order that the polishing surface ofthe cleaning member 6002 contacts the rotary drum 1004 along the outerperipheral surface of the rotary drum 1004. Moreover, the pressing forceof the cleaning member 6002 at the time of contact with the rotary drum1004 is adjusted by the tension provided to the cleaning member 6002between the rolls 6004 by the rotating and driving means.

Consequently, in a condition where the cleaning member 6002 is at thecleaning position in which its polishing surface contacts the outerperipheral surface of the rotary drum 1004, the cleaning member 6002 iselectrically connected with the housing 20 via the rolls 6004, thebearing, the ball bearing and the conductive grease, and is alsoelectrically connected with the housing 20 via the guides 6006.

In the present embodiment, the rolls 6004 and the guides 6006 constitutethe supporting member claimed in the appended claims.

In the configuration described above, the rotary drum 1004 rotates, andthe polishing surface of the cleaning member 6002 thereby contacts theouter peripheral surface of the rotary drum 1004 and the magnetic head1006, and cleans residual dirt, such as abraded powder debris frommagnetic tapes, built-up thereon.

Static electricity generated due to contact between the cleaning member6002 and the outer peripheral surface of the rotary drum 1004 and themagnetic head 1006 flows to the housing 20 via the cleaning member 6002,the rolls 6004, the bearing, the conductive grease and the ball bearing,and the static electricity also flows to the housing 20 via the guides6006 which function as supporting members.

Consequently, no static electricity is applied to the magnetic head1006, and electrostatic damage can thus be prevented.

FIG. 4 is a schematic drawing showing a variation of the cleaning deviceof the second embodiment.

In a cleaning device 60A, the rolls 6004 and the guides 6006 areprovided on a swing member 6008. The swing member 6008 is swingablysupported on the housing 20 by a supporting shaft 6010. A plunger 6014of a solenoid 6012 is connected with the swing member 6008.

The guides 6006 are connected with the housing 20 with a lead wire 6007.

The swing member 6008 is configured such that it is caused to swing byan on/off operation of the solenoid 6012. Thus, the cleaning member 6002is disposed to be able to move between a cleaning position at which thecleaning member 6002 contacts the rotary drum 1004 and a non-cleaningposition away from the rotary drum 1004.

In this variation too, as in the second embodiment, static electricitygenerated due to contact between the cleaning member 6002 and the outerperipheral surface of the rotary drum 1004 and the magnetic head 1006flows to the housing 20 via the guides 6006 and the lead wire 6007.

Consequently, no static electricity is applied to the magnetic head1006, and electrostatic damage can be prevented.

The applicant of the present invention confirmed through experiments ifthere is any difference in the preventive effect against electrostaticdamage to the magnetic head depending on whether grounding of thecleaning member to the housing is present or not.

FIG. 5A is an explanatory diagram showing measurement results of thepreventive effect against electrostatic damage to the magnetic head 1006when cleaning operations of the rotary drum 1004 are performed in astate in which the cleaning member 5004 is grounded to the housing 20 inthe first embodiment.

FIG. 5B is an explanatory diagram showing measurement results of thepreventive effect against electrostatic damage to the magnetic head 1006when cleaning operations of the rotary drum 1004 are performed in astate in which the cleaning member 5004 is not grounded to the housing20 in the first embodiment.

On the horizontal axes in FIGS. 5A and 5B, characters indicatingdifferent sample kinds of the cleaning member 5004 are shown, and thevertical axes in FIGS. 5A and 5B represent electrical resistance of thecleaning member 5004. Moreover, a circle in these figures indicates thatthe magnetic head 1006 did not suffer electrostatic damage, and a crossin these figures indicates that the magnetic head 1006 sufferedelectrostatic damage.

Samples A to F are made by including, in urethane, carbon particles eachhaving a diameter of about 20 nm at predetermined weight percentages,and the weight percentage of the carbon particles of each sample is asfollows.

Sample A: 30%

Sample B: 25%

Sample C: 20%

Sample D: 15%

Sample E: 10%

Sample F: 5%

As shown in FIG. 5A, it can be seen that if the electrical resistance ofthe cleaning member 5004 is 10¹⁰ Ω or less, electrostatic damage to themagnetic head 1006 can be prevented.

As shown in FIG. 5B, it can be seen that if the cleaning member 5004 isnot grounded to the housing 20, electrostatic damage to the magnetichead 1006 cannot be prevented even if the electrical resistance of thecleaning member 5004 is 10⁶ Ω or less.

From the experiment results, it was found that making the electricalresistance of the cleaning member be 10¹⁰ Ω or less and, at the sametime, grounding the cleaning member to the housing are effective inpreventing electrostatic damage to a magnetic head.

In the first embodiment, the cleaning member 5004 is made ofelectrically conductive resin containing carbon particles, and in thesecond embodiment, the cleaning member 6002 is made by including carbonparticles in a material of the polishing surfaces formed on bothsurfaces of a base comprising synthetic resin. However, the presentinvention is not limited thereto, and the cleaning member may be madefrom an arbitrary material as long as it has the aforesaid electricalconductivity. For example, the following materials may be used: anelectrically conductive resin made of a polymeric material in which anelectrically conductive material is contained, a semiconductor material,a polymeric material showing metallic or semiconductor-like electricalconductivity, and the like.

Moreover, although in the first and the second embodiments, the cleaningmember is supported by the supporting member made of a metal material,and the grounding of the cleaning member to the housing is performed viathe supporting member, it is sufficient that the material of thesupporting member be a material having electrical conductivity.

Moreover, the cleaning member simply needs to be grounded to thehousing. Therefore a configuration in which the cleaning member isgrounded to the housing through some other member having electricalconductivity (such as a lead wire) other than the supporting member maybe employed. Nonetheless, by grounding the cleaning member to thehousing via the supporting member, the number of parts can be decreased,and it is thus advantageous in decreasing costs.

Moreover, it is arbitrary whether to dispose the cleaning member at afixed cleaning position where the cleaning member contacts the rotaryhead, or to dispose the cleaning member so as to be movable between acleaning position and a non-cleaning position away from the rotary head.

However, the number of parts can be decreased by disposing the cleaningmember at a fixed cleaning position where the cleaning member contactsthe rotary head, and it is thus advantageous in decreasing costs.

Moreover, the timing and the duration of performing cleaning on therotary head can be set arbitrarily in a case where the cleaning memberis disposed so as to be movable between a cleaning position and anon-cleaning position at which the cleaning member is separated from therotary head. Thus, the case has an advantage in that it is capable ofexecuting cleaning at and over an optimal timing and duration for anapparatus (a magnetic tape recording and reproducing apparatus) equippedwith the cleaning device.

Moreover, in the first embodiment, the cylindrical cleaning member 5004is rotatably provided, but the cleaning member 5004 may also be providedsuch that it does not rotate.

The shape of the cleaning member is not limited to a cylindrical or tapeshape, and may be arbitrarily chosen.

It is sufficient that the housing 20 comprise at least a portion havingelectrical conductivity, and the cleaning member may be grounded to thehousing 20 at this portion of the housing 20 having electricalconductivity.

Although the invention has been described in its preferred form with acertain degree of particularity, obviously many changes and variationsare possible therein. It is therefore to be understood that the presentinvention may be practiced otherwise than as specifically describedherein without departing from the scope and sprit thereof.

1. A rotary head cleaning device for cleaning a rotary head, comprising:a cleaning member made of a material having electrical conductivity;said cleaning member contacts said rotary head and said material havingelectrical conductivity has an electrical resistance of 10¹⁰ Ω or less;and further wherein said cleaning member is grounded and contacts saidrotary head with an outer peripheral surface of said cleaning member. 2.The rotary head cleaning device according to claim 1, wherein: saidrotary head comprises a rotary drum, and a magnetic head attached tosaid rotary drum; and said magnetic head is a magneto-resistive typehead.
 3. The rotary head cleaning device according to claim 2, whereinsaid magneto-resistive type head is one of a magneto-resistive head, agiant magneto-resistive head and a tunneling magneto-resistive head. 4.The rotary head cleaning device according to claim 1, wherein saidmaterial having electrical conductivity comprises an electricallyconductive resin made of a polymeric material containing an electricallyconductive material.
 5. The rotary head cleaning device according toclaim 1, wherein said material having electrical conductivity comprisesa semiconductor material.
 6. The rotary head cleaning device accordingto claim 1, wherein said material having electrical conductivitycomprises a polymeric material having metallic or semiconductor-likeelectrical conductivity.
 7. The rotary head cleaning device according toclaim 1, wherein: said cleaning member is formed in a tape-like shape;and said cleaning member contacts said rotary head with a surface ofsaid cleaning member perpendicular to the thickness direction of saidcleaning member.
 8. The rotary head cleaning device according to claim1, wherein: said cleaning member is supported by a supporting memberhaving electrical conductivity; and said cleaning member is grounded tosaid housing via said supporting member.
 9. The rotary head cleaningdevice according to claim 1, wherein said cleaning member is disposed soas to be movable between a cleaning position where said cleaning membercontacts said rotary head and a non-cleaning position away from saidrotary head.
 10. The rotary head cleaning device according to claim 1,wherein said rotary head is a rotary head for a magnetic tape recordingand reproducing apparatus.
 11. The rotary head cleaning device accordingto claim 1, wherein: said housing comprises a portion having electricalconductivity; and said cleaning member is grounded to an electricallyconductive portion of said housing.
 12. A rotary head cleaning devicefor cleaning a rotary head, comprising: a cleaning member made of amaterial having electrical conductivity; said cleaning member contactssaid rotary head; and said material having electrical conductivity hasan electrical resistance of 10¹⁰ Ω or less; and further wherein saidcleaning member contacts said rotary bead with a surface of saidcleaning member perpendicular to the thickness direction of saidcleaning member; the cleaning member is supported by a supporting memberhaving electrical conductivity; the cleaning member is grounded to saidhousing via said supporting member; and said cleaning member is disposedso as to be movable between a cleaning position where said cleaningmember contacts said rotary head and a non-cleaning position away fromsaid rotary head.
 13. The rotary head cleaning device according to claim12, wherein said rotary head is a rotary head for a magnetic taperecording and reproducing apparatus.
 14. The rotary head cleaning deviceaccording to claim 12, wherein: said housing comprises a portion havingelectrical conductivity; and said cleaning member is grounded to anelectrically conductive portion of said housing.